This application is based upon and claims the benefit of priority from the prior Japanese Patent Application No. 2000-164216, filed Jun. 1, 2000, the entire contents of which are incorporated herein by reference.
The present invention relates to a single-substrate-processing apparatus for performing a semiconductor process, such as oxidation, diffusion, film formation, or annealing. The term xe2x80x9csemiconductor processxe2x80x9d used herein includes various kinds of processes which are performed to manufacture a semiconductor device or a structure having wiring layers, electrodes, and the like to be connected to a semiconductor device, on a target substrate, such as a semiconductor wafer or an LCD substrate, by forming semiconductor layers, insulating layers, and conductive layers in predetermined patterns on the target substrate.
In the process of manufacturing semiconductor devices, several types of heat-processing apparatuses are used for subjecting target substrates, such as semiconductor wafers, to a semiconductor process, such as oxidation, diffusion, film formation, or annealing. A single-substrate-processing apparatus, which handles wafers one by one, is known as one of these heat-processing apparatuses. The single-substrate-processing apparatus generally includes an airtight process chamber, and a worktable disposed in the process chamber for mounting a target substrate.
In the single-substrate-processing apparatus, there is a case where a wafer positionally shifts or laterally slides on the worktable, when the wafer is being placed on the worktable or the process chamber is being reduced in pressure. This is caused because the wafer temporarily falls in a floating state due to a gas present between the wafer and the worktable. For example, when a process gas in the process chamber is exhausted after a predetermined process, the pressure in the process chamber is quickly reduced from a process pressure by vacuum-exhaust. At this time, the gas present between the bottom of the wafer and the top of the worktable expands and floats the wafer up, whereby the wafer temporarily falls in a floating state and laterally slides.
In order to solve problems due to such a lateral slide of wafers, there is a countermeasure known in that a worktable is provided with a guide ring, positioning pins, or a recess. However, the countermeasure is not intended to essentially suppress or prevent a wafer from laterally sliding, but only to limit the lateral slide of the wafer to a certain range. Accordingly, when the wafer laterally slides and causes friction with an underlayer or hits the guide ring or the like, particles may be generated.
Jpn. Pat. Appln. KOKAI Publication No. 11-6069 discloses another countermeasure to the problems of laterally sliding wafers. In the technique disclosed in this publication, a single-substrate-processing apparatus of a lamp-heating type employs a thin table plate having a mount face on which three radial grooves are formed. The grooves are formed to correspond to three lifter holes in which lifter pins are respectively arranged to move a wafer up and down. The gap space between the wafer and the worktable communicates with the inner space of the process chamber through the grooves and the lifter holes. With this arrangement, it is possible to prevent the wafer from floating up or laterally sliding due to pressure changes.
However, the present inventors have found the following problems in the technique disclosed in this publication.
First, this technique does not sufficiently deal with wafers having a larger size. Specifically, as a wafer is larger, the surface area of a region distant from the lifter holes increases on the bottom of the wafer, so the release of gas from the bottom of the wafer becomes difficult.
Second, this technique does not sufficiently deal with worktables having a greater thickness, such as one with a built-in heater. Specifically, as a worktable is thicker, the conductance of the lifter holes decreases, so the release of gas from the bottom of the wafer becomes difficult.
An object of the present invention is to provide a single-substrate-processing apparatus for a semi-conductor process, which prevents a wafer from positionally shifting or laterally sliding on a worktable, when the wafer is being placed on the worktable or a process chamber is being reduced in pressure.
According to a first aspect of the present invention, there is provided a single-substrate-processing apparatus for performing a semiconductor process, comprising:
an airtight process chamber;
a worktable having a mount face configured to horizontally support a target substrate within the process chamber;
a supply section configured to supply a process gas into the process chamber;
an exhaust section configured to vacuum-exhaust the process chamber;
a heater configured to heat the target substrate through the mount face;
a plurality of lifter pins configured to move the target substrate to and from the mount face, the lifter pins being respectively disposed in lifter holes formed through the worktable;
a plurality of ventilation holes formed through the worktable; and
a plurality of ventilation grooves formed on the mount face, and comprising first ventilation grooves communicating with the lifter holes and second ventilation grooves communicating with the ventilation holes, the second ventilation grooves comprising radial grooves, which respectively have outer ends extending outward beyond a contour of the target substrate placed on the mount face;
wherein a gap space between the target substrate and the mount face communicates with an inner space of the process chamber around the worktable and the target substrate, through the first and second ventilation grooves, the ventilation holes, and the lifter holes.
According to a second aspect of the present invention, there is provided a single-substrate-processing apparatus for performing oxidation of a semiconductor process, comprising:
an airtight process chamber;
a worktable having a mount face configured to horizontally support a target substrate within the process chamber;
a pedestal standing upright in the process chamber and supporting the worktable;
a supply section configured to supply a process gas containing an oxidizing gas into the process chamber;
an exhaust section configured to vacuum-exhaust the process chamber;
a window formed in a casing of the process chamber and facing the worktable;
a UV lamp disposed outside the process chamber and facing the window, the UV lamp being configured to radiate UV rays onto the oxidizing gas above the worktable to activate the oxidizing gas;
a heater configured to heat the target substrate through the mount face;
a plurality of lifter pins configured to move the target substrate to and from the mount face, the lifter pins being respectively disposed in lifter holes formed through the worktable;
a plurality of ventilation holes formed through the worktable; and
a plurality of ventilation grooves formed on the mount face, and comprising first ventilation grooves communicating with the lifter holes and second ventilation grooves communicating with the ventilation holes, the second ventilation grooves comprising radial grooves, which respectively have outer ends extending outward beyond a contour of the target substrate placed on the mount face;
wherein the first and second ventilation grooves, the ventilation holes, and the lifter holes are arranged substantially point-symmetric with respect to a center of the mount face,
the lifter holes and the ventilation holes have openings surrounding the pedestal on a bottom of the worktable, and
a gap space between the target substrate and the mount face communicates with an inner space of the process chamber around the worktable and the target substrate, through the first and second ventilation grooves, the ventilation holes, and the lifter holes.
Additional objects and advantages of the invention will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. The objects and advantages of the invention may be realized and obtained by means of the instrumentalities and combinations particularly pointed out hereinafter.